Use SequentialSampler if curriculum_sampling is enabled with sample_p…

…acking (#2235)

src/axolotl/core/trainer_builder.py

@@ -608,8 +608,14 @@ def _get_train_sampler(self) -> Optional[torch.utils.data.Sampler]:
                     self.state.train_batch_size or self.args.per_device_train_batch_size
                 )
                 batch_max_len = train_batch_size * self.args.max_seq_length
+
+            if self.args.curriculum_sampling:
+                sampler = SequentialSampler(self.train_dataset)
+            else:
+                sampler = RandomSampler(self.train_dataset)
+
             return MultipackBatchSampler(
-                RandomSampler(self.train_dataset),
+                sampler,
                 lengths=get_dataset_lengths(self.train_dataset),
                 packing_efficiency_estimate=self.args.sample_packing_efficiency,
                 batch_max_len=batch_max_len,